Analysis of flexural hinge orientation for amplified piezo-driven actuators

In this paper, we show that aligning the hinges in a flexure-based rhombus-shaped piezo-driven amplifying mechanism increases its performance. A simplified analytical model is first proposed based on the definition of the input and the output stiffnesses of an amplifying mechanism. Approximate analytical expressions for both stiffnesses are then derived for two hinge configurations: parallel and aligned. The model predicts increases in the free stroke, the blocking force and the efficiency which are confirmed by numerical simulations. Most importantly, a reduction of the bending in the hinges is confirmed both numerically and analytically. As a matter of fact, simulations show a significant decrease (40%) of the maximal stress when the hinges are aligned.